1. Field of the Invention
The present invention relates to a catalyst composition for hydroformylation and a hydroformylation process using the same. More specifically, the present invention relates to a catalyst composition for hydroformylation of olefin compounds, comprising a specific phosphine ligand and a transition metal catalyst, and a hydroformylation process using the same.
2. Description of the Related Art
A hydroformylation reaction, wherein linear (normal) and branched (iso) aldehydes, in which the number of carbon atoms is increased by one, are prepared by reacting various olefins with carbon monoxide (CO) and hydrogen (H2), commonly called “synthetic gas”, in the presence of a homogeneous organometallic catalyst and ligand was first found by Otto Roelen in 1938 in Germany.
Generally, the hydroformylation reaction known as an oxo reaction is an industrially important reaction in the homogeneous catalyst reaction and various aldehydes including about 9.60 million tons of alcohol derivatives are produced and used all over the world through an oxo process (SRI report, November 2002, 682. 7000A) in 2001.
Various aldehydes synthesized through the oxo reaction undergo condensation such as aldol condensation, and then are converted into acids and alcohols containing longer alkyl groups through an oxidation or hydrogenation process. In addition, after condensation reaction of aldol or the like, aldehydes may be oxidized or hydrogenated and then converted into various acids and alcohols containing a long alkyl group. In particular, the hydrogenated alcohol obtained by this oxo reaction is referred to as an oxo alcohol. The oxo alcohol is widely industrially used for solvents, additives, materials of various plasticizers and synthetic lubricants.
A metal-carbonyl compound catalyst is known to be active as a hydroformylation catalyst and the industrially used catalyst is generally based on cobalt (Co) and rhodium (Rh). N/I selectivity {ratio of linear (normal) to branched (iso) aldehyde}, activity and stability of produced aldehyde depend on the kind of catalysts and ligands and operation conditions.
At present, 70% or more of oxo plants in the world utilize a low pressure oxo process in which an excess phosphine ligand is applied to a rhodium-based catalyst due to high catalyst activity, high N/I selectivity and relatively easy reaction conditions in spite of problems such as high catalyst cost and deterioration in catalyst activity caused by poisoning.
As a central metal of a catalyst for oxo reaction, a transition metal such as cobalt (Co) and rhodium (Rh) as well as iridium (Ir), ruthenium (Ru), osmium (Os), platinum (Pt), palladium (Pd), iron (Fe), and nickel (Ni) may be used. The respective metals exhibit catalyst activity in the order of Rh>>Co>Ir, Ru>Os>Pt>Pd>Fe>Ni. Co, Rh, Pt and Ru are Group VIII transition metals, which exhibit superior catalyst activity during an oxo reaction. Pt and Ru are utilized only in research applications, most oxo processes for commercial applications are based on rhodium and cobalt, and representative examples thereof include HCo(CO)4, HCo(CO)3PBu3 and HRh(CO)(PR3)3.
Ligands used for oxo processes include phosphine (PR3, in which R represents C6H5 or n-C4H9), phosphine oxide (O═P(C6H5)3) and phosphite. When rhodium is used as a central metal, a ligand that exhibits superior catalyst activity and stability, as compared to triphenylphosphine (TPP) is known to be almost not present. Accordingly, generally, a rhodium (Rh) metal is used as a catalyst for oxo processes, TPP is used as a ligand, and TPP as the ligand is used at an amount of 100 equivalents or more of the catalyst in order to improve catalyst stability.
Since among aldehydes, products of oxo reactions, linear aldehyde derivatives are generally valuable, most catalyst research has been focused on increase in ratio of linear aldehydes.
However, there is also increasing demand for techniques that can improve catalyst stability and reduce an amount of used ligand, while maintaining a suitable selectivity of iso-aldehyde.